They are not automatically unloaded when unloading the model!

* Fix loading multiple animations from .iqm file

* Fix memory leak in models_animation example

* Added export instructions to the animation example

* use raylib free

* include <stdlib.h> to appease the travis CI gods

* replace tabs with spaces

Multiple functions added and some reviewed to adapt to the new multi-mesh, multi-material and animated models.

Still a work in progress but it already works...
Current riqm API could be simplified...

Replaced old dwarf model

- Renamed Begin3dMode() --> BeginMode3D()
- Renamed Begin2dMode() --> BeginMode2D()
- Renamed End3dMode() --> EndMode3D()
- Renamed End2dMode() --> EndMode2D()

It's more educational to go through new material system, so, I decide to
remove this function to avoid students confusion...

Cat replaced by dwarf

Examples have been renamed for coherence with raylib modules and test
examples have been merged into examples folder.

View CHANGELOG for details